1. Field of the Invention
The present invention relates to an illumination control apparatus and, more particularly, to an illumination control apparatus for controlling an illumination load in response to signal outputs from a supervisory slave unit and a photosensor slave unit.
2. Description of the Related Art
A conventional illumination control apparatus is disclosed in, for example, Published Unexamined Japanese Patent Application No. 62-276608, and consists of a supervisory terminal for monitoring the ON/OFF state of an operation switch and a control terminal for ON/OFF-controlling an illumination load, these two devices being connected to a central processing unit through signal lines. This conventional control apparatus additionally comprises a timer terminal which includes a monitor section for monitoring the control state of the illumination load, a comparison and determination section for determining whether the state of the illumination load controlled in response to a timer control signal is the same as the present control state of the illumination load, and a response transmitting section for returning an inversion request signal only when the states are different from each other as a result of comparison and determination.
In such a control apparatus, it is determined whether a control state of the illumination load is the same as the present control state of the illumination load in response to a timer control signal at a predetermined time when the illumination load is to be controlled. If the control states are different from each other, the illumination load is inversion-controlled. Even if the illumination load is set in a state different from a programmed state by the operation switch, a program operation set in a timer is performed with high reliability.
When illumination is artificially controlled in accordance with a program set in a timer, however, a person's will is included in the control operation. In contrast to this, when an illuminance of natural light is detected by, e.g., a photosensor, a person's will is not included. When a photosensor is used in place of a timer, therefore, an illumination unit is unnecessarily turned on in accordance with an exclusive OR relationship between the photosensor and the operation switch.